This ear training app tries to assist you in learning 7th chords by ear.
NO SHORTCUTS HERE!
It takes work!
And if you don't have a partner to play the chords for you, good look quizzing yourself.
Say you want to practice the C seventh chords. Select C from the dropdown, click the play button and a chord will sound. You select if you think it's the Major7 or Dominant7. After you answer those correct 10 times, you move on to the next level, which adds another chord, the Minor7, then the next level adds the Half Diminished, and so on.
At any point in time you can click on the practice button which brings up a screen of all the chords, which you can click on to hear what each sounds like.
You aren't penalized for wrong answers. The goal is to learn through repetition, not penalize you for wrong answers.
You'll be surprised at how quickly you start hearing differences that you probably never would have noticed before. But this does take work, and at times you'll be frustrated. You might have a hard time getting them all, but even if just a few stick in your brain, that'll greatly increase your playing, transcribing, and composing ability.